Ignition Coil differences

[Dan Sarandrea (Phila)]

You are correct! However, I suspect that the range is very limited. I believe this because unlike modern day Bosch fuel injection, ours have a switch to compensate for higher altitude.. If the system was able to adapt to "rich" conditions, they wouldn't need that switch on the ECU...

Ed

Just as an FYI, the FI system did not account for altitude changes until somewhere in the middle of the FI run, around the '84 or maybe '85 model year. The systems that do accommodate altitude have a different Bosch part number, and the label colors are different, blue for no-altitude and gold/yellow for yes-altitude, and of course the yes-altitude ones have the little barometric sensor thingie hanging off the FI control box mounting bracket.

 

[ecohen2]

Just as an FYI, the FI system did not account for altitude changes until somewhere in the middle of the FI run, around the '84 or maybe '85 model year. The systems that do accommodate altitude have a different Bosch part number, and the label colors are different, blue for no-altitude and gold/yellow for yes-altitude, and of course the yes-altitude ones have the little barometric sensor thingie hanging off the FI control box mounting bracket.

Yup, I have the switch... No sensor...

 

[Crusader]

You are correct! However, I suspect that the range is very limited. I believe this because unlike modern day Bosch fuel injection, ours have a switch to compensate for higher altitude.. If the system was able to adapt to "rich" conditions, they wouldn't need that switch on the ECU...

Ed

Switch? I have turbo'd mine and would be very interested in how it is done and where is the switch located? Thanks,

 

[Rupunzell]

Isn't the purpose of the O2 sensor to adjust mixture so that you would not be getting a fuel dump? Ii could see this with a carb motor but not so much with an injected motor.

O2 sensor works by chemically converting the residual O2 in the hot exhaust gas into a voltage, similar to a battery. There is time required for this conversion to happen.

In the Fiat SOHC there are four exhaust ports feeding a single exhaust pipe and a single O2 sensor. This is essentially an average of the exhaust gas mixture from all four exhaust ports.

If one cylinder is mis-firing, that single cylinder will be dumping raw air-fuel mixture into the exhaust which will combine with the exhaust from the other ports causing the O2 sensor to be confused with what is happening in the exhaust. This will confuse the ECU which adjust the injector fuel spray volume. The L-jetronic is continuous fuel spray, this affects the overall fuel delivery, but will not compensate for a mis-firing cylinder as the definition of a mis-fire is intermittent function. In the case of a dead cylinder, it makes the situation much worst since that dead cylinder is a constant raw air-fuel dump into the exhaust that the O2 sensor and ECU injector control system cannot manage, going beyond the systems air-fuel adjustment range. This is why a mis-firing ignition system can easily toast the cat converter. This happens on most EFI engines including the SAAB Tronic 5 system (sequential injection, ion detonation and combustion per cylinder sensing, dynamic ignition timing per cylinder, per combustion cycle, maps for fuel, ignition advance, gear box gearing -vs- engine load and speed, tubo boost, air, water and intake air temps and a LOT more) which is WAY more sophisticated than the L-Jetronic.

Essentially, the O2 sensor and ECU system is unable to anticipate an ignition mis-fire and compensate. The O2 sensor and ECU can only react to what has happened and not before something is about to happen.


Bernice